Semiconductor devices, such as LSIs, are manufactured by performing various kinds of processes, such as film formation and etching, on a semiconductor substrate. If the surface of the semiconductor substrate is left exposed to the air after completion of these steps, elements such as transistors formed on the semiconductor substrate may be deteriorated by the moisture and the like contained in the air.
To prevent such element deterioration, the steps for manufacturing the semiconductor devices include a step of forming an insulating film to protect the semiconductor substrate from the air. This insulating film is called a passivation film. The step of forming the passivation film is preferably as simple as possible in order to reduce the costs of the semiconductor devices.    [Patent Document 1] Japanese Laid-open Patent Publication No. 2005-174990    [Patent Document 2] Japanese Laid-open Patent Publication No. 2007-311385    [Patent Document 3] Japanese Laid-open Patent Publication No. 2008-294405